This invention relates to a liquid closure device for gas conduits or pipes and which includes a container and a substantially vertical gas inlet pipe which projects at least with its lower orifice into the container.
When transporting gases in gas pipes very often the problem arises that the gas should pass or flow in one direction as unimpeded as possible whereas passage or flow in the other direction has to be absolutely prevented. Such a condition exists, for example, in gas pipes which connect a generator of inert gases (usually a combustion chamber) with an installation which uses inert gases (for example tanks for flammable liquids or explosive gases).
Liquid closure devices of this type have been described in the prior art publication "The Royal Institution of Naval Architects38 , WC (1971). In one well known arrangement, the orifices of the vertically positioned gas inlet pipe ends or extends below the water level of the container which is partially filled with water. During the normal functioning of the installation for the production of inert gases, that is where gas is transported from the generator to the installation which uses the inert gases, the inert gas must be pressed or passed through the water. For this purpose a considerable amount of energy is required which is proportional to the presssure drop of the gases which pass through. On the other hand, the gas absorbs a large amount of moisture while bubbling through the water and a large amount of this moisture has to be removed by the water separators which follow the liquid closure device. The passing of the gas through a water separator again causes a loss of pressure. Water will be pressed or passed into the vertically arranged inlet pipe if excessive pressure exists in the installation which uses the inert gas. The column of water which rises therein prevents the passage of gases into the gas generator. The height of the gas inlet pipe determines the maximum closure pressure.
In another known prior art arrangement according to Howden (see the publication quoted hereinabove) the inert gas passes through a Venturi tube after having passed through the container of the liquid closure device. The lower end of the vertically arranged gas inlet pipe is kept free of water during normal functioning of the inert gas generator by the pressure drop caused by this arrangement. Even this liquid closure device cannot operate without a considerable pressure drop, that is, a pressure drop in the Venturi tube.
Furthermore the gas is not entirely prevented from absorbing moisture. This is caused by the impinging and thereby redirecting of the inert gases upon the surface of the water which remained underneath the orifice of the gas inlet pipe. Furthermore the gas must penetrate the water in the charging and discharging phases when the water level is elevated. In these phases the takeup of moisture is particularly large.
Accordingly, an object of the present invention is to overcome the aforementioned disadvantages of known prior art arrangements and to provide a liquid closure device for gas conduits or pipes utilizing a container and a substantially vertically arranged inlet pipe which at least with its lower orifice projects into the container in such a way that a pressure drop does not occur any more, and that the absorption of moisture is prevented also during the charging and discharging phases.
According to the present invention the aforementioned objective is achieved by utilizing a container provided with regulating valves at the liquid inlet and at the liquid outlet, and also providing a fluid outlet containing a siphon with an outlet orifice on the fluid outlet being situated above the orifice on the gas inlet pipe. The container of the liquid closure device constructed in this manner may be kept empty during the whole normal working period so that the gases cannot absorb any moisture. No additional losses of pressure occurs within the liquid closure device besides the normal pressure drops normally associated with the passage of gas within a gas pipe.
The regulation of the valves for the inflow and for the outflow of liquids occurs preferably in such a way that one of both valves is closed when the other one is opened. When using such a regulation of the valves only one regulating means for both valves is needed, preferably a cylinder-piston arrangement.
It is also advantageous to provide a four-way valve instead of the two regulating valves. It is easy to fulfill the frequently needed requirement that the liquid flows constantly in the inflow pipe.
Other features which are considered characteristic of the invention are set forth in the appended claims.
Although the invention is illustrated and described in relationship to specific embodiments, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without department from the spirit of the invention and within the scope and range of equivalents of the claims.